River pirates, murderous bandits, and serial killers used this Illinois cave as their debauched hideout.

A gothic church spire sits atop this skyscraper, the tallest church in the world.

These abandoned grain silos and tunnels are an urban exploration dream.

A once-booming Mississippi River town with a history of racial violence is now eerie and mostly abandoned.

An enormous park-like oasis, full of famous Chicagoans' graves.

A lush green oasis in the middle of Chicago.

The "Grand Canyon of Southwestern Idaho" makes a spectacular gash across the flat Snake River plain.

Two geologically young and nearly circular volcanic subsidence craters, each about a half-mile in diameter, abruptly break the nearly featureless Snake River Plain.

This Idaho state park boasts the tallest single-structured sand dune in North America.

The only bridge in the United States where BASE jumping is legal without a permit year-round.

One of the "twins" in these falls on the Snake River was sacrificed for hydropower generation in the 1930s.

An impressive waterfall nestled in the cliffs of Idaho's Snake River Canyon.

This highest peak in Idaho can only be reached by traversing a formation known as "Chicken-Out Ridge."

A creek tumbles over a series of step-like rocks to create this scenic water feature.

These century-old beehive-shaped kilns were built to produce charcoal for nearby mines.

These falls, sometimes called the "Niagara of the West," still put on a good show at the right time of year.

This set of hot springs also comes with fantastic views.

It was once used as a classroom to teach mining skills to local high school students.

The largest outdoor art gallery in the Northwest United States.

This trail leads to a mine that was used as a sanctuary during the Great Fire of 1910.

A few dilapidated structures are all that remain of this deserted former silver mining town.

A former gold rush boomtown has managed to stay in business for over 100 ramshackle years.

A legal loophole makes it possible to get away with murder within this 50-square-mile section of Yellowstone.

These black pillars of volcanic basalt seem to call mountain climbers with an unbreakable siren song.